Individuals who take the TOEFL test more than once are called TOEFL repeaters. TOEFL repeaters’ test preparation behaviors are understudied and there is a lack of understanding about the interpretation of repeaters’ multiple test scores. This study investigated TOEFL iBT (Internet-based test) repeaters’ test preparation strategies and explored the relationship between repeaters’ test preparation strategies and their test performance. TOEFL iBT repeaters who received satisfactory scores in the repeated test often share their test preparation experience in TOEFL-related online discussion forums. In this study, 170 Chinese TOEFL iBT repeaters’ test preparation experience posts were manually collected from a major TOEFL test online discussion forum. The repeaters’ test-taking behaviors, test-preparation strategies, and the implementation of strategies were presented by statistical and qualitative analyses. Using repeaters’ test score changes as the outcome variable, this study ran simple and multiple regression analyses to find the relationship between repeaters’ test preparation strategies and their test score improvements in the repeated tests. The results suggest that memorizing TOEFL vocabulary, getting feedback on output samples, speed listening, practicing TOEFL Practice Online (TPO), and shadow speaking are strong predictors of repeaters’ test score gains. The findings may contribute to the understanding of the test preparation behaviors of the TOEFL iBT repeaters and provide relevant evidence to the support of the validity argument of the TOEFL iBT test. Implications of how the findings may benefit test takers, test users, and test developers of the TOEFL iBT test are also discussed.